Pressure compensated flow rate controllers

ABSTRACT

A flow controller apparatus having few moving parts that may be inserted directly into a flow line to be responsive to flow pressure and maintain the flow rate constant. The flow controller consists of a tubular frame section having an internal bore that is a revolutional chamber having a maximum cross-sectional diameter at the inlet end and tapering, either linearly or non-linearly, toward a minimum cross-sectional area across a throat portion. A control rod and differential pressure plate supported axially movably in said chamber is spring biased toward the inlet end of the chamber, and is movable in response to upstream flow pressure to adjust the cross-sectional fluid flow area to maintain a constant flow rate.

This application is a division, of application Ser. No. 808,786, filedDec. 13, 1985, now abandoned.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates generally to pressure and flow rate control offluid materials such as gas or liquid and, more particularly, but not byway of limitation, it relates to an improved flow rate controller thatis responsive to fluid flow pressure to maintain a constant flow rate.

2. Description of the Prior Art

Applicants are aware of no prior art that functions in the manner of thepresent invention wherein fluid pressure within a flow way is directlyutilized to control fluid flow through an orifice in such manner that aconstant flow rate can be maintained. There are a number of priorteachings wherein responsive members have been placed in a fluid streamfor the purpose of providing a force indication to an externalmonitoring or actuating facility. U.S. Pat. No. 3,269,181 in the name ofSeay illustrates one form of flow responsive device that is responsiveto solids flow, but the end function of this device is entirelydifferent and provides no form of fluid flow regulation. Still otherprior methods employ the basic steps of flow rate sensing withservo-controlled orifice adjustment, a very common type of flow control,but one that functions independently of the fluid pressure of fluidmaterial within the conduit.

Differential pressure, as sensed across an adjustable metering orifice,is used on an automatic flow rate controller of a type that iscommercially available from the W. A. Kates Co. of Deerfield, Ill. Thiscontroller utilizes a system of parallel fluid flow for regulation, onebranch flowing through a first adjustable orifice, the other branchapplying upstream pressure to vary a second orifice or flow passage. Yetanother type of flow control valve may be identified as the Griswoldvalve. This valve provides in-line, pressure responsive control membersfor maintaining constant flow rate within a preselected pressure range.The control structure includes a spring loaded cup with speciallydesigned orifices for movement in response to downstream pressure toregulate total fluid passage. In this case the tortuous cup orificesprovide the total fluid passage at the rated maximum pressure flow ratealong with any fluid flow at greater pressures.

SUMMARY OF THE INVENTION

The present invention provides a flow controller apparatus having fewmoving parts that may be inserted directly into a flow line to beresponsive to flow pressure and maintain the flow rate constant. Theflow controller consists of a tubular frame section having an internalbore that is a revolutional chamber having a maximum cross-sectionaldiameter at the inlet end and tapering, either linearly or non-linearly,toward a minimum cross-sectional area across a throat portion. A controlrod and differential pressure plate supported axially movably in saidchamber is spring biased toward the inlet end of the chamber, and ismovable in response to upstream flow pressure to adjust thecross-sectional fluid flow area to maintain a constant flow rate.

In addition, the use of such flow rate controller enables theconstruction of a portable type of fluid pressure and flow rate controlapparatus that is suitable for instantaneous set-up and usage in themany applications where it is necessary to reduce pressure and flow ratefrom a high pressure, high volume liquid or gas source for supply to alow pressure, low volume output requirement. The pressure apparatusconsists of an inlet coupling with primary valve control connectedthrough a pressure regulator to a relief valve, and output at reducedpressure is applied through a flow controller device, of a type to bedescribed, that is responsive to maintain a constant, reduced pressureflow rate output for conduction and use as required. A contaminantseparator may be utilized prior to the flow controller. The basicpressure apparatus may also include various optional components such asfluid cooling equipment, flow rate indicators, ancillary control valves,and a suitable form of skid base to enable easy movement and positioningat a work space.

Therefore, it is an object of the present invention to provide a flowcontroller apparatus that may be constructed inexpensively to provide adevice of relative simplicity for long life, high reliabilityapplication.

It is also an object of the present invention to provide a flowrestrictive control device that may be used to control the flow rate ofliquids or gases when the stream pressure may vary by automaticallyadjusting the cross-sectional flow area therethrough.

It is still another object of the present invention to provide a fluidpressure control apparatus to control such as air output from largecompressor equipment to adjust flow rate for best operation of pneumaticconveying apparatus.

Finally, it is an object of the invention to provide controllerapparatus for use in many applications requiring a fixed flow rate ofliquid or gas while outlet pressure may vary.

Other objects and advantages of the invention will be evident from thefollowing detailed description when read in conjunction with theaccompanying drawings which illustrate the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of a basic flow control apparatus asconstructed in accordance with the present invention;

FIG. 2 is a side view in section and idealized form of one type of fluidflow controller device;

FIG. 3 is a side view in section of an alternative form of flowcontroller device;

FIG. 4 is a view in elevation of a skid-mounted fluid pressure controlapparatus;

FIG. 5 is a top plan view of the apparatus of FIG. 4; and

FIG. 6 is a side elevation in section of the specific flow controllerdevice utilized in the apparatus of FIGS. 4 and 5.

DETAILED DESCRIPTION OF THE INVENTION

Referring to FIG. 1, the apparatus 10 may be utilized to process a highvolume, high pressure fluid flow for reduction to a reduced pressure butconstant flow rate for a particular application, e.g. a pneumaticconveying system or the like. Thus, a fluid source 12 may be such as avery high volume compressor source, and the output is applied through apressure regulator 14 of known and commercially available type forreducing the pressure down within the desired pressure range. Outputflow of fluid from the pressure regulator 14 is then applied through aflow rate controller 16, as will be further described, which functionsto maintain the fluid flow therethrough at a constant rate thereby toprovide the output reduced pressure supply 18.

FIG. 2 illustrates one form of pressure compensated fluid flow ratecontroller device 20 consisting of a tubular section that may be mountedin a gas or liquid flow line. Device 20 consists of a tubular frame 22having an inlet end 24 and an outlet end 26 and an axial chamber 27therethrough. The chamber 27 is a surface of revolution or othersuitable shape having maximum cross-sectional diameter at inlet lip 28as well as along the outlet end surface 30. A minimum cross-sectionalarea is present across a throat 32 as the interior surface 34 tapersfrom maximum diameter at inlet lip 28 to minimum diameter at throat 32;and then, a further taper surface 36 progresses from the minimumdiameter back toward the maximum diameter at the outlet end 30.

A flow restrictor 38 is slidably supported along an axis 40 ofrevolutional chamber 27. The flow restrictor 38 consists of adifferential plate 42 supported transversely across chamber 27 by anaxial rod 44. The differential plate 42 may be formed with a bevelededge 45 to optimize the response of differential plate 42 to changes inflow. The flow restrictor 38 is movably supported by a bushing-type rodguide 46 as positioned axially by a plurality of equi-spaced struts 48secured about the inner wall 30. The rod guide 46 is formed with anaxial bore 50 to slidingly receive the rod 44 therethrough, and acompression spring 52, seated between the rod guide 46 and the back sideof differential plate 42, provides a continual bias towards the inletend of chamber 27. The strength of compression spring 52, as well as thediameter of differential plate 42 and coactive minimum diameter atthroat 32, may be adjusted variously to accommodate selected pressureand volume ranges of fluid flow as will be further described below.

In operation, as the device 20 is adapted to receive gas or liquid flowtherethrough, a drop in pressure is created across the differentialplate 42 at the inlet end 24. For any pressure differential, there willbe a flow area that will give the required flow rate. Thus, thedifferential plate 42, spring 52 and tapered cylinder wall 34 down tothroat 32 are sized to give the required flow area for everydifferential pressure that may occur within the intended range of usageof the device. The flow area will be that concentric area lying betweenpressure plate 42 and tapered wall 34. It may be noted from theparticular design of FIG. 2 that when pressure plate 42 is transverse toinlet end 24, the desired flow rate is maintained with a relatively lowpressure differential across differential plate 42; and when plate 42spans across the throat portion 32, the desired flow rate is maintainedat relatively high differential pressure across the differentialpressure plate 42. In this case, the conical tapered wall 34 is a linearvariation; however, this may not necessarily be the preferred designsince some applications might require or better operate with anon-linear taper, as will be described.

When the differential pressure plate 42 is positioned within thecylinder token 34 for controlling the flow rate with a particulardifferential pressure, i.e. as appears across differential pressureplate 42, lowering of the pressure at outlet end 26 will result in anincrease in the pressure differential. Thus, the increased pressuredifferential will tend to move plate 42 toward the outlet end and willcompress the spring 52, shifting the pressure plate 42 rightward tonarrow the concentric flow orifice therearound. This then results in aconstant volumetric flow rate despite any changes in the pressure at thedownstream end.

FIG. 3 illustrates an alternative form of structure which functions uponthe same flow restriction principle as the device 20 of FIG. 2. Flowcontroller device 60 is formed from a tubular frame 62 having a uniformdiameter inside wall 64, an inlet end 66 and an outlet end 68. A minimumdiameter throat 70 is formed by a concentric ring member or orificeplate 72 suitably secured as by welding at a selected point transverselywithin inner wall 64 and at a point proximate the inlet end, this beinga design consideration. The minimum diameter of throat 70 is a selectioncontrolled by the size of the co-active flow restrictor, and theintended pressure and volume ranges. The inside of tubular frame 62forms a revolutional chamber 74 through which input gas or liquid flowmust pass for regulation.

A flow restrictor 76 consists of a tapered control plug 78 having areverse tapered conical forward face 80 as supported along chamber axis82 by means of a rod 84. The rearward tapered surface 86 is formed ofpredetermined angular relationship to control rod 84, this also being aconsideration of the minimum diameter to be regulated across opening 70,and a differential pressure plate 88 is disposed transversely on controlrod 84 at a predetermined position downstream. Control rod 84 is axiallysupported for slidable disposition in a rod guide 90 having an axialbore 92 and being supported by a plurality of struts 94. A compressionspring 96 of selected size and strength is then disposed between rodguide 90 and the differential pressure plate 88.

In operation, the flow controller device 60 receives input of gas orliquid under pressure at inlet end 66 and a drop in pressure is createdacross the differential pressure plate 88. For any particular pressuredifferential, there must be a flow area, i.e. through throat 70, whichwill give the required balance against compression spring 96 andtherefore the required flow rate. The pressure plate 88, spring 96,orifice plate 72 and control plug tapered surface 86 are all selected tobe of a size that will give the required cross-sectional flow area forevery differential pressure within the design range of the device 60.

Thus, if the control plug 78 is positioned to control the fluid flowrate with a selected differential pressure, then lowering of thepressure at outlet end 68 will effectively increase the pressuredifferential across plate 88. This increased pressure differential willthen compress the spring 96 and shift the tapered control plug 78rightward thereby to reduce the flow area thorugh orifice plate 72. Hereagain, the result is a constant fluid flow rate despite any changes inthe pressure at outlet end 68. The device 60 may be primarily used tocontrol the flow rate of liquids or gases when the downstream pressuremay vary as the device automatically adjusts the area available for flowto maintain a fixed flow rate.

FIGS. 4 and 5 are directed to an assembly package for fluid pressure andvolume regulation which utilize a flow controller device such as thosepreviously described. Thus, a pressure control assembly 100 includes ahigh pressure inlet 102 and a controlled low pressure outlet 104 asinlet fluid is controlled by an input control valve 106. Control valve106 may be such as a conventional Ball-type valve of selected size.Input valve 106 then connects to a Tee section 108 of a pressureregulator 110. Regulator 110 may be a commercially available type ofregulator, and one present design application utilizes aRobertShaw-Fulton standard type Air Pressure Regulator--5-55PSI.

Reduced pressure output from regulator 110 is then via coupling 112 to aTee section 114 and conduit 116 for tangential input into an oil andwater separator 118. The Tee connector 114 includes a relief-valve orrupture disc 120 secured thereto as connected by a sealed bushing 122.Any of various comercially available rupture disc unions may be utilizedto provide designated over pressure relief. The separator 118 may be anyof various commercial separators used at the comparable pressure range,and output from separator 118 is via conduit 124, elbow 126 and conduit128. The lower portion or base 130 of separator 118 includes a drainconsisting of the conduit assembly 132 for draining oil, water and othercontaminants from the fluid supply. A pressure sensing line consistingof a tubing 134 is connected from the pressure regulator 110 to a needlevalve 136 mounted on separator 118.

The reduced pressure gas or liquid is applied from output conduit 128 toa flow controller 140 that is similar in operation to the devicesillustrated in FIGS. 2 and 3; however, in this particular packageassembly, the flow controller 140 is a specific design as shown morefully in FIG. 6. The device 140 consists of a tubular frame 142 havingan inlet end 144 and an outlet end 146, and defining an axialrevolutional chamber 148 that has a non-linearly varying insidediameter. That is, the inside diameter varies from a maximum diameter atpoint 150 through a generally uniform arcuate narrowing to a throatportion 152 having a minimum diameter and, thereafter, enlarginglinearly to the maximum 154 at the outlet end 146. The arcuatelytapering surface 156 is about one-third the length of the linearlytapered surface 158.

A flow restrictor 160 consists of a pressure plate 162 generally alignedwith the inlet end 144 and supported normal to axis 164 and secured on amovable control rod 166. The control rod 166 is retained forlongitudinal movement by means of a rod guide 168 with axial bushing170. The rod guide 168 is axially supported by a plurality of struts 172and a force-fit pin 174 restrains control rod 166 in its traverse underforce of a compression spring 176 disposed around control rod 166between such as seating washers 178 and differential pressure plate 162.

The outer surface of tubular frame 142 includes a pair ofcircumferential grooves 180 and 182 which function in the sealingoperation. That is, and referring again to FIGS. 4 and 5, a pair ofsealed couplings 184 and 186 of the Victaulic-type are utilized to placethe flow controller 140 in the output flow conduit 128 prior toconduction through a conduit 188 to fluid output 104. The output 104 mayinclude a quick-connect coupling 190, and conduit 188 may include asight glass 192 or other means for indication of operation.

The entire pressure and flow rate control assembly 100 is mounted on asuitable skid 196 to enable moving and placement of the control assemblyin the most convenient manner. The skid 196 is suitably formed of weldedchannel construction consisting of side channels 198 and 200 connectedby respective end channels 202 and 204. A generally central partitionbrace 206 provides additional lateral support, and transverse channels208 and 210 provide a limited amount of decking space. In addition,channels 208 and 210 provide slots for convenient lifting with the forksof a forklift tractor. The weld-secured brackets 212 provide securefooting for base 130 of separator 118, and a bracket 214 and U-boltassembly 216 provide support for the apparatus inlet at control valve106.

In operation, the package apparatus 100 provides the interconnectionequipment necessary for use in reducing the pressure and flow rate froma high pressure, high volume liquid or gas source to supply lowpressure, low volume output at controlled flow rate. Apparatus 100essentially includes the pressure regulator 110 which serves to reducethe pressure down to the required level, and the serially connected flowrate controller device 140 then serves to reduce the flow rate. Thecombination also includes cleaning and control components such as inputvalve 106, relief valve structure or rupture disc 120, contaminantseparator 118 and quick couplings for connection at inlet 102 and outlet104. Still other ancillary components such as fluid cooling equipment,flow rate indicators, and the like may be included on the skid-mountedapparatus to incorporate still more complete function.

High pressure liquid or gas from a high volume source, is connected atinlet 102 for conduction through control valve 106 to the pressureregulator 110. That is, pressures on the order of 100-200 PSI at inlet102 may then be adjusted downward through pressure regulator 110 to alower pressure value. In a present design of the appratus 100, thepressure regulator 110 is used to bring the fluid pressure (air) down to45 PSI and rupture disc 120 is set to provide over pressure protectionrelative to this value. The reduced pressure fluid is then appliedthrough separator 118 for removal of oil, water or other contaminants,and output fluid pressure varying about the reduced figure is appliedthrough the flow controller device 140 for conduction to outlet 104 andwhatever the intended application.

The flow controller device 140 (FIG. 6) has been specifically designedas to spring force, throat dimensions and the like for use at theparticular reduced pressure, i.e. to provide a fluid flow output of 45PSI and lower with fixed flow rate. Thus, as may be noted from FIG. 6,the diameter of the pressure plate 162 approaches one-third of thediameter across throat portion 152 of chamber 148, and the axialposition of pressure plate 162 relative to arcuate taper proceeding frompoint 150 to throat portion 152, will define the area of the concentricflow passage. Thus, the greater the air pressure at the inlet relativeto the outlet, causing greater differential across the pressure plate162, the more the compression of spring 176, and the narrower willbecome the concentric flow passage between taper portion 156 andpressure plate 162. Accordingly, even though the outlet pressure maychange, the flow rate from the outlet will remain constant.

While the tubular frame 22 and the like have been referred to generallyas bodies of revolution defining circular inside dimension, it should beunderstood that this structure may be any tubular form defining anequi-centric chamber relative to the longitudinal axis, i.e. any chamberhaving equi-form radius for all cross-sectional dimensions. Optimallythen, the respective differential plates and flow restrictor means maybe similarly shaped in cross-section.

The foregoing discloses a novel flow controller device which, in turn,enables construction of a novel pressure and flow rate control apparatusthat may be readily employed for diverse usage to provide air or otherfluid at prescribed pressure and flow rate. The flow rate controllerdevice may be used in any of many applications that require a fixed flowrate of liquid or gas while the outlet pressure may vary. Moreparticularly, such equipment may be used to control the flow of gas suchas air from a large compressor to obtain the proper flow rate for bestoperation of a pneumatic conveying system that handles such as cement,drilling mud or the like. The skid-mounted package for pressure and flowrate control provides a very effective and less expensive alternative tothe use of dedicated compressor equipment in and around manufacturingplants since a unitary central pressure source may be readily adjustedand controlled for use in any of various satellite operations. The fluidpressure and flow rate control package or apparatus 100 convenientlygroups the necessary equipment for controlling any of pressure, flowrate, temperature, contaminants of fluid stream, etc., and alloperations are maintained interactively within a small area.

Changes may be made in combination and arrangement of elements asheretofor set forth in the specification and shown in the drawings; itbeing understood that change may be made in the embodiments disclosedwithout departing from the spirit and scope of the invention as definedin the following claims.

What is claimed is:
 1. Apparatus for controlling fluid flow rate,comprising:frame means for allowing a fluid to flow therethrough havingan inlet end, an outlet end, a throat portion therebetween and aninterior wall defining a flow chamber that is an equi-centric, elongatedvolume having a linear central axis extending between said inlet andoutlet ends, said flow chamber having a cross-sectional areaperpendicular to said central axis, that varies between a maximum at theinlet end and a minimum at the throat portion proximate said inlet end;flow restrictor means for varying the flow rate of said fluid, having across-sectional area relative to said minimum at the throat portion,said flow restrictor means being supported for axial reciprocationbetween the inlet end and said throat portion; support means forslidably supporting said flow restrictor means having a cross-sectionalarea normal to the axis of said flow chamber; and spring meanscircumferentially disposed around said support means, for biasing saidflow restrictor means toward a position in said flow chamber adjacentthe inlet end having a maximum cross-sectional area, and away from thethroat portion having a minimum cross-sectional area.
 2. Apparatus asset forth in claim 1 wherein:said frame means includes a cylindricalconduit with an inside diameter defining said flow chamber having aconstant cross-sectional area, said frame means includes an orificeplate secured transversely across said flow chamber proximate the inletend, said orifice plate having an axial orifice defining across-sectional area less than said flow chamber cross-sectional area;and said flow restrictor means includes a control plug having a taperedsurface adjacent the inlet end that presents less than thecross-sectional area of said flow chamber and tapers toward said orificeplate, and a differential plate rigidly connected to said control plugin spaced, axial alignment and approximating a selected cross-sectionalarea less than the cross-sectional area of said flow chamber. 3.Apparatus as set forth in claim 2 wherein said support meanscomprises:rod guide means for maintaining axial alignment of said flowrestrictor means, secured axially in said flow chamber adjacent theoutlet end; and rod means, slidably retained by said rod guide meansin-line with said flow chamber axis, said rod means for rigidly securingand supporting said control plug and differential plate in spacedrelationship.
 4. Apparatus as set forth in claim 3 wherein said springmeans comprises:a compression spring retained on said rod means betweensaid differential plate and said rod guide means.